Marin man and his grandmothers are the latest Internet sensations, dancing the 'Harlem Shake'

It took only 30 seconds for 22-year-old Hank Rao of San Rafael and his two octogenarian grandmothers to become the latest Internet sensations.

That's how long, or short, the video is of Rao and his grandmas dancing to "Harlem Shake," a song by electronic musician Baauer that's putting "Gangnam Style" in the pop culture rearview mirror. (So many people are making videos to the tune, more than 12,000 at last count, that a Website has been created, HarlemShakeup.com, to share them.)

Rao, who graduated from Dominican University last semester, shot the video over the weekend during a family Chinese New Year celebration at his parents' house in Southern California.

He uploaded it on Sunday, captioning it "My two grandmas attempt to do their version of the Harlem Shake." By the time he got home, it had gone viral.

As of Wednesday morning, it had 937,500 hits.

"It just kind of blew up," he said. "It had 600,000 hits in one day and it's now approaching a million. It's on a bunch of different news sites, It was on the 'Today' show yesterday morning. It's trending on the front page of YouTube. It was on CNN."

It all began after Rao, who has an online business, theluckypair.com, selling men's underwear, saw a "Harlem Shake" video on reddit, a site that bills itself as "the front page of the Internet." Unlike "Gangnam Style," "Harlem Shake" has no steps to learn. It's entirely free form.

"It was hilarious, and I thought I might as well make my own since my grandparents are a little bit crazy and love dancing," he said. "They're both in their 80s, but they have their energy still. I showed them one of the videos and they were pretty excited to do it themselves."

The video opens with Rao dancing alone before being joined by his wildly gyrating grandmothers, Po Tsang and Yu Qiong Cai. "Harlem Shake" videos often feature scantily clad dancers, but Rao and his grannies kept their clothes on.

"I told them, 'Go crazy when the bass drops,'" he said. "Those are their own movements they came up with. I didn't really tell them to do anything."

Rao has gotten messages from several licensing groups that place advertising on viral videos, including the company that handled the famous "Charlie Bit My Finger" video.